In the discussion that follows, reference is made to certain structures and/or methods. However, the following references should not be construed as an admission that these structures and/or methods constitute prior art. Applicant expressly reserves the right to demonstrate that such structures and/or methods do not qualify as prior art against the present invention
Electrostatic chucks, and/or susceptors, are employed to support a wafer, substrate or another type of workpiece during the manufacture of semiconductor devices. Typical electrostatic chucks include an electrically conductive electrode that is mounted on a pedestal and covered by a seating surface. High-temperature processes such as sputter-etching and ion bombardment use high-purity ceramic material for seating surfaces to reduce contamination. Other seating surfaces include electrically insulative, dielectric material, high-purity ceramic, metal oxide, and other materials such as sapphire (single-crystal Al2O3). Different types of electrostatic chucks include bipolar designs based on dual electrodes in the chuck and monopolar chucks with a single electrode.
During manufacturing processes in plasma processing apparatus, the workpiece sits on top of the seating surface and a voltage source electrically biases the electrode so that electric charge accumulates in the electrode and the seating surface. The applied voltage also induces an equal and opposite charge on the rear surface of the workpiece. The accumulated electric charge generates an electrostatic force that attracts and clamps the workpiece against the seating surface of the electrostatic chuck.
While the workpiece is clamped, various processes can be employed, such as chemical vapor deposition, ion implantation, ion beam milling and reactive ion etching. During the various processes, substrate temperatures are regulated with confined gas such as helium that flows onto the backside of the workpiece.